Google has what I think are the most transparent and user friendly controls for visualizing what personal data is collected, and disabling it (most often per product, for ex. disable location history and YouTube viewing history, but enable personalized ads).
- For most of the products mentioned in the blogpost (YouTube, Search, ...), people can just go to MyActivity [0] and delete any data they want to. They can also disable data collection here. [1]
- Emails received in Gmail are no longer used for advertisement in other Google products, only used for Gmail ads, and features like searching your emails, spam prevention, parsing orders/flights/etc. to display them in the app. Also note that emails received in GSuite ("enterprise Gmail") were never parsed for these purposes. [2]
[0] https://myactivity.google.com/
[1] https://myaccount.google.com/activitycontrols
[2] https://www.nytimes.com/2017/06/23/technology/gmail-ads.html
Important disclaimer: I work at Google [but only voicing my own opinions, as it goes], and only working there because I realize they are doing all they can to respect user privacy.